CO oxidation over CuOx/TiO2 catalyst: The importance of oxygen vacancies and Cu plus species

作者：Chen, Wei; Xu, Jue; Huang, Fajun; Zhao, Chaoying; Guan, Yingqiao; Fang, Yarong; Hu, Jinpeng; Yang, Weiwei; Luo, Zhu^*; Guo, Yanbing^*

来源：Applied Surface Science, 2023, 618: 156539.

DOI：10.1016/j.apsusc.2023.156539

• Oxygen vacancies
• Cu plus
• brookiteTiO2
• CO oxidation

It is well documented that the existence of oxygen vacancies and active Cu species can improve CO oxidation activity over TiO2 substrate. Herein, TiO2-supported copper catalysts (CuOx/TiO2) with different ratio of oxygen vacancies (Ov) and Cu+ has been synthesized. The existence and amount of Ov and Cu+ species were characterized by transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and electron paramagnetic resonance spectrum (EPR). The synergetic effect between Cu+ and oxygen vacancies was investigated in terms of O2 temperature-programmed desorption (O2-TPD), H2 temperature-programmed reduction (H2-TPR) and in situ DRIFTS spectra. Cu+ is the adsorption site for CO molecules, the abundant Ov can significantly activate molecular oxygen, which effectively oxidize the adsorbed CO molecules. The most suitable ratio between Cu+ and Ov has been confirmed. The CuOx/TiO2(Cu+ rich) catalyst (51% Cu+, 26.3% Ov) shows superior CO oxidation activity (T90 = 136 degrees C) compared to CuOx/TiO2(Ov rich) catalyst (39% Cu+, 28.5% Ov, T90 > 350 degrees C). This work provides comprehensive investigation of the role for abundant oxygen vacancies and Cu+ in CO oxidation reactions.